Acellular nerve xenografts based on supercritical extraction technology for repairing long-distance sciatic nerve defects in rats

Compared to conventional artificial nerve guide conduits (NGCs) prepared using natural polymers or synthetic polymers, acellular nerve grafts (ACNGs) derived from natural nerves with eliminated immune components have natural bionic advantages in composition and structure that polymer materials do not have. To further optimize the repair effect of ACNGs, in this study, we used a composite technology based on supercritical carbon dioxide (scCO2) extraction to process the peripheral nerve of a large mammal, the Yorkshire pig, and obtained an innovative Acellular nerve xenografts (ANXs, namely, CD + scCO2 NG). After scCO2 extraction, the fat and DNA content in CD + scCO2 NG has been removed to the greatest extent, which can better supported cell adhesion and proliferation, inducing an extremely weak inflammatory response. Interestingly, the protein in the CD + scCO2 NG was primarily involved in signaling pathways related to axon guidance. Moreover, compared with the pure chemical decellularized nerve graft (CD NG), the DRG axons grew naturally on the CD + scCO2 NG membrane and extended long distances. In vivo studies further revealed that the regenerated nerve axons had basically crossed the CD + scCO2 NG 3 weeks after surgery. 12 weeks after surgery, CD + scCO2 NG was similar to autologous nerves in improving the quality of nerve regeneration, target muscle morphology and motor function recovery and was significantly better than hollow NGCs and CD NG. Therefore, we believe that the fully decellularized and fat-free porcine ACNGs may be the most promising “bridge” for repairing human nerve defects at this stage and for some time to come.